This invention relates to a pin filter connector for reducing electromagnetic interference in electrical devices by attenuating various frequencies applied to the pin. More particularly, it refers to a filter connector having a series of thick film capacitors with holes within the various elements of the capacitors, each accommodating an electrically conductive pin.
Filter connectors for attenuating high frequency interference from electrical devices are well known from several patents, e.g., U.S. Pat. Nos. 3,538,464, 4,126,840, 4,144,509 and 4,187,481. In each of these patents, a capacitor employed in the filter is a series of ceramic layers forming a monolithic structure. Thick film capacitors are also well known from U.S. Pat. No. 4,274,124. Although monolithic capacitors are currently used in filter connectors, it has not been practical heretofore to substitute thick film capacitors such as shown in U.S. Pat. No. 4,274,124 for these monolithic capacitors. Problems have occurred in designing a thick film capacitor for a filter connector which has a low enough inductance to attenuate high frequencies.
In recent years, the common usage of computers and particularly home computers has resulted in the generation of significant additional amounts of high frequency electromagnetic signals interfering with other electrical devices. For the purpose of reducing the output of such signals, the United States Federal Communications Commission (FCC) has promulgated regulations requiring attenutation at their source. See 47 CFR 15, Subpart J.
Available monolithic capacitor structures used in filters are not cost effective for use in electronic equipment such as the personal computer. Furthermore, such structures have low strength and frequently crack or fracture during fabrication or installation and even in use. Accordingly, what is needed is a filter connector employing thick film capacitors of low inductance. In this regard, a useful commercial filter attenuates electromagnetic signals at least 30 decibels (dB) at a frequency of 1000 megahertz (MH.sub.z).